Mercury F87Z-13480-AA Stop Light Switch Assembly

The brake light switch, also known as the brake pedal position switch or brake light switch, informs the PCM when the brakes are being applied. This switch closes when brakes are applied and opens when they are released, and is mounted on the brake pedal. The brake light circuit is controlled by this switch, and issues such as burned-out bulbs or other circuit problems can cause the engine to idle roughly. Therefore, it's important to check the brake light switch operation when troubleshooting any rough-idle problems. To identify the functions of connector terminals, wiring diagrams can be used. Disconnect the switch connector and connect your voltmeter positive (+) lead to the connector terminal that provides battery positive (B+) voltage to the switch. Connect the negative (-) meter lead to a good ground. Turn the ignition On and read the meter. It should indicate more than 10 volts or close to battery voltage. Connect an ohmmeter to the switch terminals and manually open and close the switch. The meter should alternate from continuity to an open-circuit reading as the switch is opened and closed. Also, check continuity from the switch to the brake light bulbs. Replace any burned-out bulbs or damaged wire looms. Replacement of the switch is covered.